A new dynamic inflow model for vertical‐axis wind turbines

Delphine De Tavernier,Carlos S. Ferreira

doi:10.1002/we.2480

Abstract

AbstractThis paper presents a new dynamic inflow model for vertical‐axis wind turbines (VAWTs). The model uses the principle of Duhamel's integral. The indicial function of the inflow‐ and crossflow‐induction required to apply Duhamel's integral is represented by an exponential function depending on the thrust coefficient and the azimuthal position. The parameters of this approximation are calibrated using a free wake vortex model. The model is compared with the results of a vortex model and higher fidelity computational fluid dynamic (CFD) simulations for the response of an actuator cylinder to a step input of the thrust and to a cyclic thrust. It is found that the discrepancies of the dynamic inflow model increase with increasing reduced frequency and baseline thrust. However, the deviations remain small. Analysing the application of a finite‐bladed floating VAWT with non‐uniform loading and validating it against actuator line CFD results that intrinsically include dynamic inflow shows that the new dynamic inflow model significantly outperforms the Larsen and Madsen model (which is the current standard in fully coupled VAWT models) and enhances the modelling of VAWTs.

Highlights

Offshore wind turbine technology has made significant and rapid progress since the first offshore wind farm was installed in 1991.1 We advanced from fixed platforms to floating structures to be able to overcome deeper water depths
This paper presents a new dynamic inflow model for vertical-axis wind turbines (VAWTs)
Analysing the application of a finite-bladed floating VAWT with non-uniform loading and validating it against actuator line computational fluid dynamic (CFD) results that intrinsically include dynamic inflow shows that the new dynamic inflow model significantly outperforms the Larsen and Madsen model and enhances the modelling of VAWTs

Summary

Introduction

Offshore wind turbine technology has made significant and rapid progress since the first offshore wind farm was installed in 1991.1 We advanced from fixed platforms to floating structures to be able to overcome deeper water depths. The operational conditions are significantly different, raising the question whether other concepts such as vertical-axis wind turbines (VAWTs) could be more suitable and allow a reduction in the cost of energy. A fundamental difference between onshore and offshore turbines is the additional complexity introduced by the motions of the floating platform.[1] Turbines are translating and rotating in three dimensions, as visualised, causing dynamic inflow conditions at the rotor. In some modelling techniques such as computational fluid dynamics or vortex methods, phenomena like the dynamic inflow effect are represented inherently since the velocity field as a result of a variable force field and/or incoming flow is physically modelled in space and time. Simpler momentum-based models are often opted for; they need additional correction models to cope with unsteady effects such as dynamic inflow.[2]

Objectives

Methods

Results

Conclusion